Cameron Diaz always struck me as sensible. Maybe because she never joined Scientology, or married anyone patently ridiculous, despite toiling for a decade and a half at the coalface of Hollywood A-listiness. Maybe because she gives a damn fine impression of not taking herself too seriously.

The actress told Cosmopolitan magazine that being a woman and admitting you didn't want children is taboo. "I think women are afraid to say that they don't want children because they're going to get shunned ... I have more girlfriends who don't have kids than those that do. And honestly? We don't need any more kids. We have plenty of people on this planet."

Diaz, who is 36, didn't go as far as to say that she definitely does not want children. But to be openly, loudly undecided on the issue - at the point when her biological clock should be ticking so loudly that she can hardly sleep, eat or think about anything else - is to be brave enough, frankly. It's an admission that invites suspicion and pity. To be a thirtysomething woman in 2009 and not want a child so desperately that you think you might die is simply not allowed.

In February, I wrote a column for Observer Woman about not wanting children. I am 37, nearly a year to the day older than Diaz and I just don't. I never have.

Unlike Diaz, I did not know that voluntary childlessness is an unacceptable crime to cop to. I thought I was merely expressing an opinion. I thought that people who want - or have - children, would accept that I do not, just as I accept their choice. After all, it's my (notional) babies I am rejecting, not theirs.

I was wrong.

I stated my case. I listed my reasons, even though it annoys me that the child-free have to justify their status. No one ever asks a parent why they have kids. But I explained that I like my life as it is, my lifestyle, my career. I explained that I had felt this way for 30 years - and that even though all the things that were supposed to change my mind (love, a long-term relationship, pressure from breeding contemporaries) had happened to me, I remain resolutely childless.

I explained that I like the potential of my childless existence: to travel, sleep, read, drink, watch HBO box sets, have feckless fun.

I talked about how difficult it is to be child-free, when popular culture fetishises parenthood in general and motherhood in particular. When the dramatic arc of all TV dramas, of all rom-coms, is dependent on someone becoming pregnant and finding true happiness as a consequence. Babies are the newest archetype on the happy ending, therefore not wanting them is tantamount to not wanting to be happy.

I talked about how weird it is to be disconnected from this baby-crazy culture. Like being sober while everyone else is drunk. I talked about how strange it is to not even care whether or not I'm infertile, when apparently it's all anyone else thinks about.

Was I antagonistic? Possibly. I tried not to be, but I am passionate about this. I was certainly a bit sensational, a bit flippant. The headline referred to the rise of the "dummy mummy" generation - an inflammatory turn of phrase.

The reaction to the piece was terrifying. Emails and letters arrived, condemning me, expressing disgust. I was denounced as bitter, selfish, un-sisterly, unnatural, evil. I'm now routinely referred to as "baby-hating journalist Polly Vernon".

So yes, Cameron Diaz, I can tell you from experience that you are right. Admit that you don't ache for children with every fibre of your being and you will be shunned. Shunning's the tip of the iceberg. I wish I'd been shunned. Shunning would have been blissful, relatively.

The furore's blown over; my childlessness endures. I've registered a gender split in the way people respond to it, if it comes up socially.

Women might think I'm in denial, but they let me get on with it now. Men, meanwhile, are astounded. Flummoxed. They become aggressive, sneering. They psychoanalyse me, they try to work out what's wrong with me. Who knows why? Perhaps they feel rejected. Perhaps the idea that there are women at large who are not actively pursuing their sperm is an out-and-out affront to a certain kind of man. The same men who have spent years believing that all women secretly want to trap them into commitment and fatherhood, probably.

For whatever reason, I've been pulled up on my wanton childless status, loudly and at length, by three different men, in three different pubs, over the course of the last fortnight alone.

Here's the thing: we need to stop pretending that childlessness isn't happening to us. It is. The birth rate in Europe is in steep decline. We know this. We know that, currently, 40% of UK university graduates aged 35 are childless and that at least 30% will stay that way permanently. We know that much of this childlessness is involuntary or, at least, unconsidered, the consequence of infertility, a lack of opportunity or leaving it too late.

But some of it will be like mine - cherished, rigorously maintained, valued. For everyone's sake, it's good to have that sort of a blueprint on a life without children. Childlessness is going to be a feature in many of our lives; we need to start seeing it as a choice, a valid option, rather than a failing. We certainly need it not to be taboo.

We need to stop making the voluntarily childless feel like they have a guilty secret. We need to stop shunning or vilifying the likes of me (in this instance, at least), and, much more importantly, Cameron Diaz and her mates.